樟子松枯梢病的侵染规律

对樟子松枯梢病、健组织病菌的分离、孢子萌发和接种试验等研究结果表明，樟子松枯梢病是一种寄主主导性病害。引起该病的松壳色二孢[Diplodia pinea(Dem.)Kickx]可在历年病树上的针叶、芽、梢、枝和果鳞上越冬，又可在健康树上的针叶、芽、梢、枝和果鳞上潜代侵染。其潜伏侵染带菌率：健康樟子松越冬各部位比当年生各部位潜伏带菌率高，分别为20％－70％和6％－30％，其中以针叶、梢、枝和每年4，5月份、9，10月份潜伏带菌率最高。病害的初次侵染源主要来自历年病树上病菌子实体飞散出来的分生孢子，借风和雨水淋洗传播，种子上不带菌。病菌可直接侵入当年嫩梢和嫩针叶，也可通过伤口、气孔侵入针叶、芽、梢和枝。潜伏期7－14d,繁殖期23－28d。

Infection Law of Shoot Blight of Pinus sylvestris var. mongolica

Through separation of pathogens from diseased or healthy tissues of Pinus sylvestris var. mongolica, spore germination and inoculation test, the research results show that shoot blight of P. sylvestrls var. mongolica is a kind of host - leading disease, Diplodia pinea, which is the pathogen that cause the disease, can live through the winter on needles, buds, tips, branches and bud scale of cones of diseased pines, and also infect potentially on needles, buds, tips, branches and bud scale of cones of healthy pines. The potential infection rate of different positions that survived the winter of healthy pines is much higher than that of different positions which are newly born, and is 20%-70% and 6% -30% separately. The po-tential infection rate is the highest of needles, tips and branches when separating period is from April to May and from Sep-tember to October. First infection source of the disease is mainly conidiospores which came from fructifications survived the winter for different years, spreading by wind and rain, which flew off from the leaves and branches of the diseased P. syl-vestris var. mongolica and seeds don't carry pathogens. The pathogen can infect the newly born tips and needles, but can not infect old ones without wound, it can also invade needles, buds, tips and branches through wound and air - hole, po-tential growth phase of the disease is 7 - 14 d, reproduction phase is 23 - 30 days.